Those with the blood type A, B or AB could be dramatically more likely to develop some types of deadly cancer, research shows.
Meanwhile, being O negative or positive could be somewhat protected from ultra-deadly pancreatic cancer.
A recent study on 50,000 Iranians found those with type A, B or AB blood — around half the UK population — have a 55 per cent higher risk of developing stomach cancer, compared to those with the O type.
Those with A blood are also a sixth more likely to get bowel cancer, the study found.
Other research, conducted in 2016 on nearly 18,000 adults, found people with the AB blood type had a 45 per cent higher chance of developing liver cancer.
This same study discovered people with the O and AB blood types had about a sixth lower chance of developing pancreatic cancer.
The most common blood type in the UK is O positive, followed by A positive and A negative.
AB negative is the most uncommon, accounting for just one per cent of the population.
Having a particular blood type could leave you at increased risk of certain cancers, research suggests
Experts are unsure exactly why certain blood types are at increased risk of cancers, particularly those that form in the digestive tract.
One theory is that different blood types produce different immune system responses to threats like bacteria, triggering changes in cells that increase the odds of cancer developing.
However, other experts have urged caution about interpreting links between blood type and cancers.
They highlighted that participant numbers in studies are often small, and the trials often fail to account for other factors that increase cancer risk like alcohol intake or being a smoker.
There are four main blood types which are then each split into two other sub groups, positive or negative with O+ and A+ being the most common.
Together these two blood types account for around 65 per cent of all people in the UK, according to the NHS.
Blood type is inherited by genes passed on by your parents, and it cannot be changed.
You can find out your blood type with a simple procedure called ABO typing which analyses a small sample of your blood.
Do-it-yourself tests are available online, for instance on Amazon, with prices starting from £9.99.
You can also book a blood test with a private clinic, which can cost under £100 and provide results within two days.
Those who donate blood on the NHS can discover their type for free.
The health service’s blood donation scheme tells all donors their personal blood type after they give their first sample.
Donors typically receive their information about a week later.
Those who have had their blood taken in hospital may also be able to ask their doctor what their blood type is.
